4.0 seems to be the community average. It takes a different mindset to achieve much more than that, but it's possible. You'll find high speed is your worst enemy as the drag goes up radically with speed. Unlike a car that usually enriches the mixture during hard acceleration, it isn't as much a factor with an EV. But, not keeping a steady speed and using the brake a lot versus mainly one-pedal driving does make a major hit in efficiency. Well, that's true for an ICE, too, but when your range isn't great in the first place, you notice it more. If you have the active cruise control, that helps, too.
2011 535i x-drive GT, 2014 i3 BEV